What Is <base href>?
Most of all Angular routing apps must have the <base> element to the index.html or layout page in the <head> tag.
When using the PathLocationStrategy, need to tell the browsers what will be prefixed to the requested path to generate the URL.
You can specify a base URL like this –
<base href="/">
OR
<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>My Demo Apps</title>
<base href="/">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="icon" type="image/x-icon" href="favicon.ico">
</head>
<body>
<app-root></app-root>
</body>
</html>
So if you had an Angular route defined like this –
{ path: 'users', component: UserComponent, data:{ title:'User List'} }
If <base href="/" >, the route become “/users”.
If <base href="/angular" >, the route become “/angular/users”.
For
more detail kindly refer the link - https://www.code-sample.com/2018/05/angular-5-6-7-routing-and-navigation.html